广州市售酸奶中乳酸菌的耐药性评估

Antibiotic Resistance of Lactic acid bacteria in Yogurt from Guangzhou

研究广州市售酸奶中乳酸菌对不同种类抗生素的药物敏感性。从市售酸奶中分离并鉴定乳酸菌,采用纸片扩散法检测分离菌株对18种抗生素的药物敏感性;E-test方法对耐药菌株进行最低抑菌浓度测定。从31份市售保质期内商标注册酸奶中分离鉴定出48株乳酸菌,其中25株嗜热链球菌(Streptococcus thermophilus)、20株保加利亚乳杆菌(Lactobacillus bulgaricus)、3株副干酪乳杆菌(Lactobacillus paracasei)。48株乳酸菌对卡那霉素、链霉素均耐药;对头孢他啶、头孢噻肟、红霉素均敏感;对环丙沙星、庆大霉素、万古霉素等呈现出不同程度的耐受性;79.2%(38/48)表现出多重耐药性;E-test分析表明,除了保加利亚乳杆菌MR10的MIC为256μg/mL以外,所有万古霉素耐药菌株对万古霉素的MIC均大于1024μg/mL。不同品牌酸奶分离菌株对抗生素具有不同的耐受性,均有多重耐受性出现,应加强其耐药性连续监测及安全评价。

The aim of this study was to evaluate the antibiotic sensitivity of Lactic acid bacteria isolated from commercially available yogurt in Guangzhou. The bacteria isolated from 31 commercially available yogurt samples（used before expiry date） were identified by physiological and biochemical reactions and 16 s rDNA sequence analysis. The sensitivity of these strains to 18 different antibiotics was determined using Kirby-Bauer method. The minimum inhibitory concentration（MIC） of the drug-resistant strains in this study was determined by the Epsilometer test（E-test）. In all, 48 isolates were identified, including 25 Streptococcus thermophilus strains, 20 Lactobacillus bulgaricus strains, and 3 Lactobacillus paracasei strains. All strains were found to be susceptible to ceftazidime, cefotaxime, and erythromycin; resistant to kanamycin and streptomycin; and showed different degrees of resistance to ciprofloxacin, gentamicin, and vancomycin. Moreover, multi-drug resistance（resistance to ≥3 antibiotics） was detected in 79.2% of isolates. The E-test results showed that MIC for all vancomycin-resistant strains was greater than 1024 μg/mL, except that for Lactobacillus bulgaricus MR10（256 μg/mL）. Strains from different yogurt samples showed resistance to different drugs, and multi-drug resistance was observed in lactic acid bacteria. Therefore, continuous monitoring of antibiotic resistance and safety evaluation of lactic acid bacteria is recommended.